Hitherto, as this type of walking assistance device, there has been known one having a load transmitting assembly, a foot-worn assembly to be attached to a foot of a user, and a leg link provided between the load transmitting assembly and the foot-worn assembly (refer to, for example, Japanese Patent Application Laid-Open No. 2007-20909). According to this device, at least a part of the weight of a user is supported by the leg link through the intermediary of the load transmitting assembly to reduce load acting on a leg of the user, thereby assisting the walking.
In the conventional example described above, the foot-worn assembly includes a shoe having a sole, which is a ground contact member on which a foot of the user is rested, and a connecting member, which connects the shoe to a joint provided at a lower end of the leg link. The connecting member is formed like a stirrup, into which a toe portion of the user can be inserted, and is attached to the shoe.
Further, in the conventional example described above, tread force sensors are provided on the sole, in one location adjacent to the heel of a foot of the user and in another location adjacent to a toe (at the proximal end of a big toe), to detect a tread force of the user. Further, the support force provided by the leg link is variably controlled according to the tread force of a leg of the user detected by the tread force sensors.
In the stirrup-shaped connecting member of the aforesaid conventional example, a foot of the user is inserted into the connecting member, so that the freedom of the motion of the foot will be limited, thus inconveniently making the user feel restrained. Hence, it is desired to secure the freedom of foot motions so as to provide more comfortable fit of the foot-worn assembly.
However, merely securing the freedom of foot motions presents the following problem. An influence of a habitual walking pattern of each user will prominently manifest, occasionally resulting in a major load being applied to the outer side in the lateral direction of a foot or a major load being applied to the inner side in the lateral direction thereof. Thus, the tread force sensors provided in only a total of two locations, one adjacent to the heel of a foot and the other adjacent to the toe, as in the aforesaid conventional example, fail to accurately detect the tread forces of the user.